Heya Jenn. I really like this style with the thick lines and how you've been able to use these to great effect to impress upon emotion and character. The top one which you can't make out properly looks pretty cool, quite possibly because it is black and white with a grey shading in between. If you wanted to make the tortise a bit more friendly looking, take away some of the sharp edges on his mouth and replace them with 'smoother corners'.